In order to investigate how teachers' use of textbooks creates different kinds of opportunities for student learning, this study focused on teachers' selection and enactment of problems and tasks from the textbooks and their influence on the cognitive demand placed on students. By drawing on data from three elementary teachers in the USA, two of which used a reform-oriented textbook--"Math Trailblazers" and one a commercially developed textbook--this study examined kinds of problems the teachers chose and ways in which they enacted those problems in relation to the cognitive demand of the problems. In particular, we attended to the kinds of questions the teachers asked in enacting the problems and ways in which those questions influenced the cognitive demand of the textbook problems. This study also identified critical issues involved in teacher decision-making on task selection and enactment, such as the match between teachers' goals and those of the textbooks, and teachers' perception of textbook problems. Based on the results of the study, we discuss implications for teacher education and professional development.